The scandal has prompted Democrat chairman Albert Ho Chun-yan, a defeated candidate in the race for the top job, to ask the High Court to approve late requests for a legal challenge to the result.

'Our case will be based on the grounds that Mr C.Y. Leung, during the election, made false representation or statements in public, thereby misleading the Hong Kong people to believe that he had no illegal structures at his properties,' Ho said, after securing a unanimous endorsement in a Democrat central committee meeting.

'This is particularly so when he pointed a finger at Mr Henry Tang during a public debate, accusing Mr Tang of maintaining a huge illegal structure in his residence, thereby totally shattering his own credibility.'

According to the law, Ho should have filed a petition within seven working days or a review within 30 days after the result was declared on March 25. But he said the court could use discretion to accept late requests, particularly where a judicial review was concerned.

Whether he could file the writ before Leung takes office on July 1 depended on when his legal advisers, who include senior counsels Martin Lee Chu-ming and Hectar Pun Hei, could complete the paperwork.

Meanwhile, contract workers spent nine hours yesterday dismantling the illegal cover on a parking space and a 40 sq ft storage room, two out of the four structures that the Buildings Department found in an inspection at Leung's home last Friday. The main gate was also deemed an illegal structure.

But it is expected to take two weeks for the 240 sq ft unauthorised basement to be filled in. A trellis and glass enclosure were torn down last week after they were exposed by the media. At least six crane trucks were deployed by various media organisations to observe the progress of the work inside the HK$500 million property.

Leung offered another public apology yesterday, but insisted that he never intended to cover up the illegal structures at his home.

'I am very disappointed in myself too and I feel sorry for letting my supporters down,' he said. 'After I bought the house, my knowledge was that it contained no illegal structures. So I had never thought about checking my house when society discussed various illegal structure cases.'

The Democrats, Civic Party and Labour Party said they wanted a special question-and-answer session before July 18, but the Democratic Alliance for the Betterment and Progress of Hong Kong - whose lawmakers asked for more details from Leung on the case - questioned the need.

Chief Executive Donald Tsang Yam-kuen commented on the case for the first time, saying Leung 'has tried his best to be candid' in explaining the case.